A common question among frugal Medicare beneficiaries is: "Can you have more than one Medicare supplement plan?"

While the short answer is no — by law, Medigap insurance providers are not allowed to sell more than one such plan to any one beneficiary — it's important to understand how these Medicare supplement plans work so you can make the best decision for your financial and health care needs. Here's what you need to know:

What Is a Medicare Supplement Plan?

A Medicare supplement plan, which is often referred to as a "Medigap plan," is private health insurance designed to help the policyholder bridge the financial gaps in their Medicare coverage. Your Medicare supplement plan can help you pay for some costs that aren't covered by Medicare such as deductibles, co-payments and coinsurance.

These plans are different from Medicare Advantage plans, also known as Medicare Part C plans. Medicare-approved private companies offer these private insurance plans, which include Medicare parts A and B and sometimes drug coverage (Medicare Part D). In effect, these plans allow policyholders to receive all their Medicare insurance through the private insurance company.

A Medicare supplement plan only supplements your Medicare benefits, while a Medicare Advantage plan provides you with a way to get those Medicare benefits. You cannot hold both a Medicare supplement plan and a Medicare Advantage plan at the same time.

How Does a Medicare Supplement Plan Work?

If you carry a Medicare supplement plan, you'll pay your insurer a monthly premium on top of the Part B premium you pay to Medicare.

When you have a covered health cost, Medicare will pay its share of the Medicare-Approved Amount before your Medicare supplement pays its portion. While these supplement plans can help you bridge the gap between the amount Medicare pays and the amount you owe, that doesn't mean you pay nothing out of pocket.

These policies each have their own limits and requirements, and supplement plans don't generally cover certain services such as long-term care (non-medical care for daily activities), vision or dental care, hearing aids, eyeglasses or private-duty nursing.

Can You Have More Than One Medicare Supplement Plan?

Since Medigap plans help Medicare beneficiaries fill in the coverage gaps for the Medicare program, it makes sense that beneficiaries might want to increase their coverage by purchasing more than one Medicare supplement plan.

Unfortunately, insurers aren't legally allowed to sell more than one Medicare supplement plan to any one individual. It is also illegal for any insurer to sell you a Medicare supplement plan if you already have a Medicare Advantage plan.

What Are Other Options for Affording Health Care in Retirement?

Since there's no option for doubling up on Medicare supplement plans, how else can retirees reduce their health care costs? Here are some helpful options:

• Medicare Advantage: Savings with one of these plans may be greater than with a Medicare supplement plan.
• Medicaid: Depending on your income, you may be eligible for free or low-cost coverage through Medicaid.
• Annuities: These financial products may help you supplement your fixed income, which can help you afford health care.
• Roth IRA: These vehicles give you the ability to access money tax-free and without required minimum distributions, giving you more financial options for health care.

The Bottom Line

Retirees can't have more than one Medicare supplement plan or one at the same time as a Medicare Advantage plan. To cut costs on health care, start by calculating whether a supplement or an Advantage plan will save you the most money.

You can also see if you're eligible for Medicaid, which would qualify you for free or low-cost health care coverage. Finally, planning ahead for your health care costs with financial products, like annuities or a Roth IRA, can help you be prepared.